Injecting Missing Content-Type Header into Python Flask Webhooks
Posted on Wed 04 December 2024 in DevOps • 1 min read
Introduction
We recently had an issue where one of our 3rd party providers decided
that it would be a good idea to remove the Content-Type header
from the webhooks that they send to our application, breaking the
contract of the webhook format.
Our application relies heavily on the webhooks for receiving status updates and the output from the 3rd party application, and our customers were negatively impacted by this unannounced change.
Automatically injecting the missing Content-Type headers
Fortunately, it is possible to implement a simple work-around for this issue in a Python Flask application as follows:
@app.before_request
def before_request():
# Only handle POST requests to /webhook endpoints
if request.method == 'POST' and '/webhook/' in request.path:
content_type = request.headers.get('Content-Type', '')
# If Content-Type is not set or is not application/json
if 'application/json' not in content_type.lower():
# Try to parse the data as JSON
try:
# Force Flask to parse JSON data even if Content-Type is not set
if request.data:
request.get_json(force=True)
# Modify the request headers to include Content-Type
request.environ['CONTENT_TYPE'] = 'application/json'
except Exception as e:
# If JSON parsing fails, return 400 Bad Request
return make_response(jsonify({
'stage': 'self',
'status': 'error',
'msg': 'Invalid JSON data',
'detail': str(e)
}), 400)